Structure Data of Free Polyatomic Molecules
915
LIF
C13H10Ar
State
Energy [eV]
r0(C13H10…Ar) [Å]
Reference
9H-Fluorene – argon (1/1)
(weakly bound complex)
~
X 1A'
0.0
3.42(3)
[1]
Cs
(effective symmetry class)
(large-amplitude motion)
~
A 1A''
4.182
3.42(3)
[1]
A molecular beam was formed by expanding a
mixture of 1% fluorene and argon through a
supersonic nozzle. Fluorescence was excited
by a frequency doubled dye laser, collected using
spatially selected optics and detected by a
photomultiplier and photon counting system.
Rotational analyses of the spectra yield rotational constants for the ground and the excited
states of the complex. From these values the coordinates of the Ar atom with respect to the
principal axes of the fluorene molecule are found to be x = 0.53(7), y = 0, z = 3.42(3) Å.
The sign of x is not determined. The large-amplitude motions of the argon atom in the
complex prevent a determination of the change in the structure of the molecule upon
electronic excitation. Further studies with fully-deuterated fluorene C13D10 and argon [2]
fail to alleviate these problems.
[1] Meerts, W.L., Majewski, W.A., van Herpen, W.M.: Can. J. Phys. 62 (1984) 1293.
[2] van Herpen, W.M., Meerts, W.L.: Chem. Phys. Lett. 147 (1988) 7.
Landolt-Börnstein
New Series II/28D
. Ar